Apparatus for transmission of music from a central studio to a plurality of subscribers



M y 1952 J. L. BURNETT ET AL 2,595,510

APPARATUS FOR TRANSMISSION OF MUSIC FROM A CENTRAL STUDIO TO A PLURALITYOF SUBSCRIBERS Filed March 20, 1948 STATION I BY M 1 Gtfornegs iPatented May 6, 1952 APPARATUS FOR TRANSMISSION OF MUSIC FROM A CENTRALSTUDIO TO A PLU- RALITY OF SUBSCRIBERS.

John L. Burnett and Bert Smith, Kansas City, Mo., assignors to ModernMusic, Inc., Kansas City, Mo., a corporation of Missouri ApplicationMarch 20, 1948, Serial No. 16,096

This invention relates to apparatus-for transmission of music from acentral studio to a subscriber having a plurality of receiving stationsequipped for receiving transcribed music and for carrying on aconversation with the studio operator.

The principal object of the invention is to provide for operation of anyone of the subscriber stations to carry on a conversation with thecentral studio operator without interference with any of the otherstations reception of transmitted music.

Other objects of the invention are to provide separate transmissionlines for music and conversation; to provide a single speaker at eachstation adapted to be connected with the transmission lines to serve asa microphone as well as a speaker; to provide for reversing voice inputamplification; to provide each station with a coin operated relay forestablishing connection through the conversation line with the centralstudio and which operate to open circuit of the other stations with theconversation transmission line without interference with music beingreceived at the other stations; to provide coin operated relays so thatwhen any one is operated the other relays function to open theconversation circuits of the other stations with respect to theconversation transmission line; and to provide means actuated by anoperator at the central studio for re-establishing the coin operatedrelays to open a closed circuit and to re-establish the ability of theother coin operated relays to be operated by a patron at any one of thestations.

In accomplishing these and other objects of the invention we haveprovided improved electric circuits and controls thereof, the preferredforms of which are illustrated in the accompanying drawing wherein:

The single figure is a diagrammatic View of the electric circuits andassociated apparatus embodying the features of the present invention.

Referring more in detail to the drawing:

I designates the circuits at a central studio, 2 control circuits at a,remotely located subscribers place of business which are connectedby'separate conversation and music transmission lines 3 and 4respectively and individual coin control station circuits '5 whereby acustomer may insert a coin at any one of a subscribers stations andeffect automatic connection with the central studio through theconversation transmission line 3 without interference by any otherpatrons station and without interference of the music trans.

scams.- (0!. re-63) mitted from the central studio through the musictransmission line to the other patrons stations.

Connected in each station circuit 5 is a speaker 63, transformer I, acoil holder relay 8, a master relay 9, switches Ill-l I, a line busysignal [2, and a binding post strip [3. The master relay includescontact points Pl to PI2 inclusive which are operated by a magnetwinding 14. The switch I0 is adapted to be operated upon insertion of acoin and includes contacts PIA, P2A and P3A. The binding post stripcarries a plurality of binding posts B! to B9 inclusive which areinterconnected to corresponding binding posts of the other stations. Thecontact PIA of the switch It] is grounded as at l5 and the contact PEAis connected through the magnet winding M of the master relay switchwith the binding post B6 by means of a conductor [6. The other contactP3A of the coin control switch is directly connected with the bindingpost B! by a conductor H. The binding posts BI and B2 are connected withthe busy signal l2 by conductors l8 and [9 which are energized uponclosing of the switch I l. The coin holding relay 8 has one sidegrounded and the other side connected by a conductor 20 with the contactP6 of the master relay switch. The contacts Pl P2, P4, P5 and Pl areconnected with the binding post B3, B6, B8, B5 and B4 by conductors 2|,22, 23, 24 and 25 respectively. The contacts P3 and P10 of the mastercontrol relay are connected with the transformer l of the speaker byconductors 26 and 21.

In operation of the coin control circuits thus described, insertion of acoin closes the switch It to energize the master relay by currentflowing between the binding post 6 through the conductor l6, contact PZAand PIA and ground l5. This actuation of the master relay closes contactP9 and P12. Simultaneously a circuit is closed to the studio circuitslater described through a circuit comprising the ground connection PIAof the switch It! and contact P3A, conductor I! and binding post I. Theimpulse through the master relay. causes the master relay to stay inclosed position as the contacts P9 and PH maintain flow of currentthrough the magnet winding 54 after the switch II] is opened.

The coin stop or coin holding relay 8 of the other patrons stations areenergized through the contacts P2 and P4 of the relay which wasenergized by insertion of a coin. The switches II of the other stationsare closed by the coin stop relays of said other stations to energizethe signals thereof to indicate that one subscribers station is beingused for communication.

The binding posts of each patron station are interconnected by lineconductors 28 to 35 so that all of the binding posts of the stations areconnected in parallel.

The control station circuits include two telephone input circuits 36 and3'! that are inductive- 1y coupled with the transmission lines 3 and 4.The input 31 supplies the music circuit 38 which includes a suitablestage amplification as indicated by the tubes VI, V2, V3 and V4.Amplified music impulses are passed from the transformer 39 of the finalstage of amplification through a conductor 49 which leads to bindingpost B5 of a binding post strip 4| having binding posts Bl to B9 fromwhich the lines 28 to 35 extend to the patrons stations 5.

The control circuits are also connected with the voice transmission line3 through conductors 42 and 43 with switches 44 and 45 having con tactsPIB, P213 and P3B, P4B, P513 and PBB, re-

spectively. The switches are operated by a relay coil 46 and areconnected with the binding posts 6 and I of the contact strips 4| byconductors 4! and 49. The contacts PIB and P4B are connected with acurrent supply of substantially 55 volts through conductors 49 and 50,the contacts P2B and P5B being connected with the conductors 42 and 43previously described. The contacts P3B and PBB are connected byconductors 5| and 52 with a reversing switch having switch sections 53and 54. The section 53 of the switch has contacts PIC, P20, P30, P40,P50 and P60. The section 54 of the switch has contacts P10, P80, P90,PIBC, Pl I and H20. The contacts P20 and P80 are connected by conductorsand 52 and the contact PIC is connected with the contact P50 by aconductor 55. The contact P30 is connected with the contact P40 by aconductor 56. The contacts P and P90 are similarly connected with thecontacts P|90 and P|20 by conductors 51 and 58. The contacts P50 andP||0 are connected with the binding and 66, the contacts 64 and 55 beingconnected with grounds and the contact 85 with the conductor 61 leadingto the grid circuit 68 of a vacuum tube 59. The other grid of the tubeis connected by a conductor that is connected with the B-voltage supplyconductor 1| of the music circuit. The plate of the tube is connectedwith the primary of a transformer 12 and the secondary ol thetransformer is connected with the contacts P30 and P90 of the switches53 and 54. The grid circuit of tube 69 is also connected to a similartransformer 13 having its primary connected with the contacts P60 and P|of the switch sections 53 and 54. The switch 63 is operated from thestudio through a signal circuit 14 that is connected with the input 36.The signal current is passed through a filtering circuit indicated at 15and imposed on the grid of a vacuum tube 76. The plate terminals areconnected with 2, relay winding 11 of the switch 63 by a conducor 8.plied with a B-voltage through a conductor 19 that is connected with theB supply conductor H of the music circuit.

Connected in the conductors 5| and 52 on the line side of condensers 80and 8| that are con- The opposite side of the winding is supnectedtherein is a relay winding 82 for operating a switch 93, one contact ofwhich is connected with a five ampere twenty-four volt current supplythrough a conductor 84 and the other contact is connected by a conductor85 with the conductor 41.

The studio apparatus includes a coin registering mechanism 86, a studiovoice amplifier 87, a studio amplifier for the subscribers voice 88, amusic preamplifier 89, and a relay signal generator 90. The mechanisms81 and 88 are connected with a switch 9| through conductors 92-93 and94-95. The switch 9| includes contacts PID, P2D and P3D, P4D, P5D, PbD,P'ID, P8D, P9D, P|9D, PI ID and PIZD. The conductors of the voicetransmission line 3 are connected with the contacts PID, PZD, P'ID, P8D,P9D and PI 0D. The signal generator 99 is connected with the contactsP||D and P|2D by conductors 96 and 91. a

The music preamplifier 89 is connected with the conductors of the musictransmission line by conductors 98 and 99. The coin register mechanism86 is connected with a transformer I90 through a switch |0| operated byan electromagnet I!) energized by a push button switch NH. The wires 94and of the studio voice preamplifier are connected with the contacts P3Dand P4D. The conductors 92 and 93 from the studio voice amplifier 81 arealso connected with the music line through a switch I92 by conductorsI03 and I04. Conductor I06 connects the contacts PlD and P9 with oneside of the voice line 3 and a conductor I05 connects P8D and PIUD withthe other side of the voice line.

Normally the switches 44 and 45 have the contacts P2B-P3B and P5B-P5Bclosed. The normal position of the reversing switch sections 53 and 54are such that the P2C-P30, P5C-P50, P80-P90, and PI |0-P|20 are closedwhile the other contacts are open so that these switches are normally incondition to pass voice currents from any one of the patrons stations tothe studio. The contacts of the switch 83 are normally closed and thecontacts of the switch 53 are normally open. The normal position of theswitches 9 at the patrons stations are such that the contacts P3 and P5,P4 and P6, and PH) and PM are closed so that the customers stations areall ready to receive music currents transmitted from the studio. Thecoin operated switches l0 and signal switches II are also normally open.

If desired a thank you signal I2 is connected across the relay windings4 of the respective patrons stations to indicate that contact is madewith the studio.

Assuming that the circuits and associated apparatus are connected asdescribed and that all of the switches are in their normal position, apatron at one of the stations in the customers place of business mayinsert a coin to close contacts PIA, P2A and P3A so that there is a24-volt current through conductor 84, switch 83, conductor 85, conductor41, relay winding 46, conductor 48, binding post of the strips 4| andI3, conductor l1, contacts P3A and PIA to ground l5. This flow ofcurrent energizes the relay winding 46 to open the contacts P2B and P3Band P53 and P63 and momentarily close the contacts PIB, P2B and P43, P5Bsending an impulse of current over'the line wires 3 to the studio toenergize the coin register mechanism 86 so that the studio operator isadvised that a patron desires to carry on a conversation. Closure of thecontacts PIA, PZA, P3A also causes a flow in the conductor 41,

binding post I of the strip 4!; relay winding [4, conductor l6 andground I5, which impulse of current operates the relay switch 9 to closethe contacts P9 and H2 to ground thereby establishing a holding circuitfor the relay 9. Upon operation of the relay switch 9 a current flows inconductor 23, contacts P2 and P4, conductor 22 to the other customersstations so that a current flows through the closed contacts P4 and P5of the relay switches of the other stations to energize the coin holderwindings 8 at those stations for closing the contact switches l I.Closing of the contact switches II at the other stations causes flow ofcurrent to signals of the other stations. Energization of the signalsindicates that one of the stations is in communication with the centralstudio. Operation of the winding 8 also rejects any coins that may beinserted at those stations so that they will not be effective inactuating the switches l until the normal conditions of the circuitshave been re-established by the operator of the studio as laterdescribed.

After the impulse of current has occurred in the relay 46, the switches42 and 43 return to their normal operating condition so that contactsP23 and P3B are closed and contacts P53 and,

P63 are closed. The relay winding I4 remains energized to hold contactof PI in engagement with P3, P2 with P4, P1 with Pm and P9 with PIZ.Upon closing of the contacts Pl, P3 and P1, PH) of switch 9, the speaker6 may be used as a microphone so that the customer may talk to theoperator of the studio, the circuit being completed through theconductors 25 and 21, contacts P'I-PI U and contacts Pl-P3 of switch 9,conductors 25 and 2|, binding posts -3 and 4 of strips l3 and 4|,normally closed contacts of the reversing switch sections 53 and 54 andconductors 42 and 43 which connect with line wires 3.

The studio operator answers by actuating the reversing switch sections53 and 54 so that voice currents from the studio will be passed in theproper direction through the amplifying tube 69. This is effected by theoperator sending a low frequency current (60 cycles) over the voice linewires to the input 36 through the filters 15 to the amplifying tube 16from where the amplified current passes through the relay 1! to closethe contacts 66, 65, 52 and64. A twenty-four volt current then passesthrough normally closed switch 83, conductor 60, winding 59, contacts 62and 64 to ground, thereby energizing the winding 59 to change theposition of the reversing switch sections 53 and 54. The contact PICwill then engage the contact P20, P40 the contact P5C, contact PHJC thecontact PHC, and contact P'IC the contact P80. The voice currents fromthe studio then pass to the input side of the tube 69 and the outputside is connected with the speaker transformer winding 1.

The operator of the studio may then talk to the customer at thesubscribers station. After the conversation has been completed betweenthe studio operator and customer, the operator at the studio proceeds tore-establish the normal position of the switch 9. This is effected bypushing the button Nil" which sends a current impulse over the voiceline wires of proper voltage to energize the relay 82 and momentarilyopen the switch 83 which interrupts the twentyfour volt current supplyto the relay winding I4, thereby re-establishing the normal position ofthe contacts for switch 9. Return of the contacts of the switch 9 totheir normal position reestablishes the coin holding mechanism andsignals at the other stations and the voice line is again open to thestudio.

The operator then transmits the desired musical composition record andconnects the music amplifier in circuit with the line wires 4 and themusic current will be received at the amplifying mechanism 38 of thecontrol station and theamplified current will be carried by theconductor 40 to the binding posts 5 of all of the stations.

During playing of the composition, a customer at any one of the-stationsmay carry on a conversation with the studio operator without interferingwith the music reception at the other stations since the relay switchfor that station automatically opens connection with the music circuitsand establishes voice connection with the studio through separate linewires.

What we claim and desire to secure by Letters Patent is:

1. In a voice transmitting and receiving system including a studio, acontrol station situated remotely from the studio and a plurality ofpatron stations at the control station, a single pair of line conductorscomposing a single telephone circuit connecting the studio with thecontrol station for transmitting voice currents between the studio andany one of the patrons stations, a current operated speaker at eachpatron's station adapted to serve as a microphone, means at the controlstation for amplifying the voice currents over said line conductors ineither direction, actuating means at each of the patron stations forsending a current impulse over said line conductors to the studio,holding means at the patrons stations adapted to be energized by saidactuating means at any one of the patron stations to prevent the otherstations from communicating with the studio, a switch mechanism at eachpatron station actuated by the current impulse for actuating the holdingmeans at the other patron stations and to connect the speaker in circuitwith the voice current amplifying means at the control station, currentconducting means connecting the amplifying means with said lineconductors, and means for sending current impulses from the studio oversaid single pair of line conductors for rendering the amplifying meansefiective so that voice currents from the studio are adapted to beamplified by the amplifying means at the control station for re ceptionat a patron's station sending the current impulses to the studio.

2. In a voice transmitting and receiving system including a studio, acontrol station situated remotely from the studio and a plurality ofpatron stations at the control station, a pair of line conductorsconnecting the studio with the control station for transmitting voicecurrents between the studio and any one of the patrons stations, acurrent operated speaker at each patrons station adapted to serve as amicrophone, means at the control station for amplifying the voicecurrents over said pair of line conductors, actuating means at each ofthe patron stations for sending a current impulse over said pair of lineconductors to the studio, holding means at the patrons stations adaptedto be energized by said actuating means at any one of the patronstations to prevent the other stations from communicating with thestudio, a switch mechanism at each patron station actuated by thecurrent impulse for actuating the holding means at the other patronstations and to connect the speaker in circuit with the voice currentamplifying means at the control station, current conducting meansconnecting the amplifying means with said pair of line conductorsincluding reversing switches for reversing flow of current through theamplifying means, a relay means for actuating the reversing switch, andmeans at the studio for sending current impulses over said pair of lineconductors for energizing the relay means actuating said reversingswitches so that voice currents from the studio are adapted to beamplified by the amplifying means at the control station for receptionat a patrons station sending the current impulses to the studio.

3. In a voice transmitting and receiving system including a studio, acontrol station situated remotely from the studio and a plurality ofpatron stations at the control station, a pair of line conductorsconnecting the studio with the control station for transmitting voicecurrents between the studio and any one of the patrons stations, acurrent operated speaker at each patrons station adapted to serve as amicrophone, means at the control station for amplifying the voicecurrents, means at the studio for sending and receiving voice currentsover said pair of line conductors, actuating means at each of the patronstations for sending a current impulse over said pair of line conductorsto the studio, holding means at the patrons stations adapted to beenergized by said impulse actuating means at any one of the patronstations to prevent the other stations from communicating with thestudio, a switch mechanism at each patron station actuated by thecurrent impulse for actuating the holding means at the other patronstations and to connect the speaker in circuit with the voice currentamplifying means at the control station, current conducting meansconnecting the amplifying means with said pair of line conductorsincluding reversing switches for reversing flow of current through theamplifying means, a relay means for actuating the reversing switch,means at the studio for sending current impulses over said pair of lineconductors for energizing the relay means actuating said reversingswitches so that voice currents from the studio are adapted to beamplified by the amplifying means at the control station for receptionby the speaker at a patrons station sending the current impulses to thestudio, and means energized at the studio for re-establishing saidmechanisms to normal position after completion of conversation betweenthe studio and patrons station.

4. In a voice transmitting and receiving system including a studio, acontrol station situated remotely from the studio and a plurality ofpatron stations at the control station, line conductors connecting thestudio with the control station for transmitting voice currents betweenthe studio and any one of the patron stations, means connected with theline conductors for amplifying said voice currents, music currentsending means at the studio, separate line wires connecting the musiccurrent sending means with the patron stations, and current directionchanging means for rendering the amplifying means effective in eitherdirection of voice current flow.

5. In a voice transmitting and receiving system including a studio, acontrol station situated remotely from the studio and a patrons stationat the control station, a speaker at the patrons station, amplifyingmeans at the control station, line conductors connecting the studio withthe control station for transmitting voice currents through theamplifying means to and from the speaker, music current sending means atthe studio, separate line wires connecting the music current sendingmeans with the patrons station, and current direction changing means forrendering the amplifying means effective for amplifying the voicecurrents in either direction.

JOHN L. BURNETT. BERT SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

